Experimental and numerical study on the interaction between holes and fissures in rock-like materials under uniaxial compression

Holes and fissures, regarded as typical defects, dominate a critical role in the mechanical behavior of rock. To investigate the effect of different horizontal distances L or L′ between the centroids of holes and fissures on the mechanical properties of pre-flawed rock-like material, two types of rock-like material specimens with holes and fissures are fabricated and subjected to uniaxial compression using Digital image correlation (DIC), Acoustic emission (AE) monitoring, Computerized tomography (CT) scanning, and two-dimensional Particle flow code (PFC2D). These results demonstrate that the peak strength, peak strain and elastic modulus all show a monotonically nonlinear decrease with increasing L or L′. Based on the DIC and CT methods, three rock bridge coalescence modes can be distinguished: tensile-tensile, shear-shear and tensile-shear modes. Moreover, the damage of the rock-like specimens, in the entire loading process, exhibits notable progressive failure characteristics in the strain localization zones. The crack initiation and coalescence cause the deformation curve to undergo a stress drop with a surge in the AE events and in the accumulated AE counts from AE monitoring. There is good agreement between the numerical simulation results and the experimental testing results, which further heighten the instability mechanism of defective rock engineering structures.